This 3D printed cast could be the future of healing broken bones

The Cortex Cast is a 3D-printed alternative to traditional plaster and fibreglass casts

Jake Evill

If you've ever had a broken limb, you know how unpleasant a cast
can be. They're bulky, uncomfortable and are basically a blank
canvas for embarrassing sketches from your friends. But the
plaster and fibreglass variety is also cheap and, frankly,
good enough to not prompt much investment in innovation.

Jake Evill was all too familiar with this problem. After
breaking his hand in what he tongue-in-cheek calls a "heroic
rescue" of his friend during a fight, the recent graduate of
Victoria University in Wellington, New Zealand, was saddled with a
plaster cast for a few months. "I was surprised by just how
non-user friendly those cumbersome things are," Evill said.
"Wrapping an arm in two kilos of clunky, and soon to be smelly and
itchy, plaster in this day and age seemed somewhat archaic to
me."

The 3D-printed brace follows the contours of the
arm

Evill figured there had to be a better solution (there wasn't).
So the young designer set about creating his own. Called
the Cortex
cast, Evill's new take on the plaster cast is a 3D-printed
brace that follows the contours of the arm. Though still just a
concept, Evill's Cortex will be an injury-localised exoskeleton
that is lightweight, washable, ventilated and recyclable. Not bad
for a school project. The young designer began by researching the
structure of the bone. He found that the trabecular, the tiny
lattice-shaped structures that form the inner tissue of a bone, to
be the perfect inspiration. "It was this honeycomb structure that
inspired the Cortex pattern because, as usual, nature has the best
answers," he said. "This natural shape embodied the qualities of
being strong whilst light just like the bone it is protecting
within."

The idea is that patients would have their fracture x-rayed and
the injured limb 3D-scanned. A computer would then determine the
optimal pattern and structure of the cast, with denser material
focused on the fractured area of the bone to provide more support.
Evill's current prototype is the product of a jerry-rigged 3D
scanner that he hacked from an Xbox Kinect. The makeshift scanner
had to be manually rotated around the arm in order to get a read,
which left the scanned shape in need of some touch ups in a program
like Zbrush. From there, the cast was sent off to Shapeways in the
Netherlands and printed in a nylon plastic. The resulting cast will
typically be 3 millimeters-thick and under 500 grams.

Evill notes that the Cortex cast is still very much in the
development stage. He's currently working to nail down the optimal
material for the cast and refine the scanning process (no hacked
Kinect would be nice, he says). Next steps is working with a
hospital to fully test the prototype and finding a
manufacturer who can help make the Cortex Cast a
reality. "There is much work to be done to bring the idea to
fruition," he says. "And I am actively seeking partners to work
with in order to make it a reality."